WPF C# - 不正确的鼠标位置坐标

Question

我想通过在图像上绘制矩形来绘制选区，但选区似乎有​​很大的偏差。这是我的代码。

EdgeDetectionWindow.xaml

    <Window x:Class="SenpiCHC.EdgeDetectionWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:SenpiCHC"
        xmlns:codeg="clr-namespace:System;assembly=mscorlib"
        mc:Ignorable="d"
        Title="EdgeDetectionWindow" Width="1270" Height="720"
        WindowState="Maximized"
        WindowStyle="None">
    <Window.Resources>
        <ObjectDataProvider x:Key="dataFromEnum" 
                            MethodName="GetValues"
                            ObjectType="{x:Type codeg:Enum}">
            <ObjectDataProvider.MethodParameters>
                <x:Type TypeName="local:SelectedEdgeDetectionType"/>
            </ObjectDataProvider.MethodParameters>

        </ObjectDataProvider>
    </Window.Resources>
    <Grid>
        <StackPanel>
            <Image x:Name="imgDynamic" 
                   MouseDown="ImgDynamic_MouseDown"
                   MouseMove="ImgDynamic_MouseMove"
                   MouseUp="ImgDynamic_MouseUp"
                   Width="1000"
                   Height="562"/>
            <Button Content="Select file" 
                Margin="30"
                Width="100" 
                x:Name="selectFileBtn"
                Click="SelectFileBtn_Click"/>

            <ComboBox Margin="10"
                      Width="100"
                      x:Name="edgeDetectionCbox"
                      SelectionChanged="EdgeDetectionCbox_SelectionChanged"
                      ItemsSource="{Binding Source={StaticResource dataFromEnum}}">
            </ComboBox>

            <Button Content="Detect now!" 
                    Margin="30"
                    Width="100" 
                    x:Name="detectBtn" 
                    Click="DetectBtn_Click"/>
        </StackPanel>
    </Grid>
</Window>

EdgeDetectionWindow.xaml.cs

 public partial class EdgeDetectionWindow : Window
{

    Image<Bgr, byte> _imgInput;

    private bool IsSelecting = false;
    private double X0, Y0, X1, Y1;
    private Bitmap ImageCopy;

    public EdgeDetectionWindow()
    {
        InitializeComponent();
    }

    private void SelectFileBtn_Click(object sender, RoutedEventArgs e)
    {
        OpenFileDialog openFileDialog = new OpenFileDialog();
        if (openFileDialog.ShowDialog() == true)
        {
            Uri fileUri = new Uri(openFileDialog.FileName);
            imgDynamic.Source = new BitmapImage(fileUri); // Why bitmapimage? //put the imagefile into the window
            ImageCopy = new Bitmap(openFileDialog.FileName);

            _imgInput = new Image<Bgr, byte>(openFileDialog.FileName);
        }
    }

    private void ImgDynamic_MouseDown(object sender, MouseButtonEventArgs e)
    {
        IsSelecting = true;
        X0 = e.GetPosition(imgDynamic).X;
        Y0 = e.GetPosition(imgDynamic).Y;
    }

    private void ImgDynamic_MouseMove(object sender, MouseEventArgs e)
    {
        if (!IsSelecting) return;


        //Save the final point
        X1 = e.GetPosition(this.imgDynamic).X;
        Y1 = e.GetPosition(this.imgDynamic).Y;

        //Make a bitmap to display the rectangle
        Bitmap bm = new Bitmap(ImageCopy);

        //Draw the rectangle
        using (Graphics gr = Graphics.FromImage(bm))
        {
            gr.DrawRectangle(Pens.Red,
                (float)Math.Min(X0, X1), (float)Math.Min(Y0, Y1),
                (float)Math.Abs(X0 - X1), (float)Math.Abs(Y0 - Y1));
        }

        //Display the rectangle
        imgDynamic.Source = BitmapToImageSource(bm);
    }

    private void ImgDynamic_MouseUp(object sender, MouseButtonEventArgs e)
    {
        if (!IsSelecting) return;
        IsSelecting = false; //reset the value

        //Display the rectangle
        imgDynamic.Source = BitmapToImageSource(ImageCopy);
    }

    private void EdgeDetectionCbox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {

    }

    private void DetectBtn_Click(object sender, RoutedEventArgs e)
    {

        if (edgeDetectionCbox.SelectedItem.ToString().Equals("Canny"))
        {
            //Receive input from inputbox
            CannyInputDialogue popup = new CannyInputDialogue();
            popup.ShowDialog();
            int tresh = int.Parse(popup.Tresh);
            int treshLinking = int.Parse(popup.TreshLinking);

            //Do canny
            //Create grayscale
            Image<Gray, byte> _imgCanny = new Image<Gray, byte>(_imgInput.Width, _imgInput.Height, new Gray(0)); //canny  with 0 intensity gray image
            _imgCanny = _imgInput.Canny(tresh, treshLinking);

            //Display the image because imgDynamic.Source cannot display image from emgucv directly
            Bitmap display = _imgCanny.ToBitmap();
            imgDynamic.Source = BitmapToImageSource(display);


        }
        else if (edgeDetectionCbox.SelectedItem.ToString().Equals("RobertCross"))
        {
            //Do robertcross

        }
        else if (edgeDetectionCbox.SelectedItem.ToString().Equals("Laplacian"))
        {
            //Do laplacian
            LaplacianInputDialogue popup = new LaplacianInputDialogue();
            popup.ShowDialog();
            int apertureSize = int.Parse(popup.ApertureSize);
            //Do grayscale
            Image<Gray, byte> _imgGray = _imgInput.Convert<Gray, byte>(); //somehow it has to be converted(?)

            //Do sobel
            Image<Gray, float> _imgLaplacian = new Image<Gray, float>(_imgInput.Width, _imgInput.Height); //canny  with 0 intensity gray image
            _imgLaplacian = _imgGray.Laplace(apertureSize);

            //Display the image because imgDynamic.Source cannot display image from emgucv directly
            Bitmap display = _imgLaplacian.ToBitmap();
            imgDynamic.Source = BitmapToImageSource(display);

        }
        else if (edgeDetectionCbox.SelectedItem.ToString().Equals("Sobel"))
        {
            //Receive input from inputbox
            SobelInputDialogue popup = new SobelInputDialogue();
            popup.ShowDialog();
            int xorder = int.Parse(popup.Xorder);
            int yorder = int.Parse(popup.Yorder);
            int apertureSize = int.Parse(popup.ApertureSize);

            //Do grayscale
            Image<Gray, byte> _imgGray = _imgInput.Convert<Gray, byte>(); //somehow it has to be converted(?)

            //Do sobel
            Image<Gray, float> _imgSobel = new Image<Gray, float>(_imgInput.Width, _imgInput.Height); //canny  with 0 intensity gray image
            _imgSobel = _imgGray.Sobel(xorder, yorder, apertureSize);

            //Display the image because imgDynamic.Source cannot display image from emgucv directly
            Bitmap display = _imgSobel.ToBitmap();
            imgDynamic.Source = BitmapToImageSource(display);

        }


    }

    BitmapImage BitmapToImageSource(Bitmap bitmap)
    {
        using (MemoryStream memory = new MemoryStream())
        {
            bitmap.Save(memory, System.Drawing.Imaging.ImageFormat.Bmp);
            memory.Position = 0;
            BitmapImage bitmapimage = new BitmapImage();
            bitmapimage.BeginInit();
            bitmapimage.StreamSource = memory;
            bitmapimage.CacheOption = BitmapCacheOption.OnLoad;
            bitmapimage.EndInit();

            return bitmapimage;
        }
    }
}

我已经尝试将 e.GetPosition() 参数放到 this 或 imgDynamic 中，但它仍然相差很大。有什么解决方法吗？如果我的代码非常混乱，我很抱歉，因为我仍在努力了解更多信息。

Answer 1

为了在图像上绘制选择矩形，您可以简单地在图像顶部添加一个带有 RectangleGeometry 的 Path 元素，如下所示：

<Canvas>
    <Image Source="C:\Users\Public\Pictures\Sample Pictures\Koala.jpg"
           MouseLeftButtonDown="ImageMouseLeftButtonDown"
           MouseLeftButtonUp="ImageMouseLeftButtonUp"
           MouseMove="ImageMouseMove"/>

    <Path x:Name="selectionPath" Stroke="Magenta" StrokeThickness="2"/>
</Canvas>

使用这些事件处理程序：

private Point mousePos;

private void ImageMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    var image = (Image)sender;

    image.CaptureMouse();
    mousePos = e.GetPosition(image);
    selectionPath.Data = new RectangleGeometry(new Rect(mousePos, mousePos));
}

private void ImageMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    var image = (Image)sender;

    image.ReleaseMouseCapture();
    selectionPath.Data = null;
}

private void ImageMouseMove(object sender, MouseEventArgs e)
{
    var rect = selectionPath.Data as RectangleGeometry;

    if (rect != null)
    {
        var image = (Image)sender;

        rect.Rect = new Rect(mousePos, e.GetPosition(image));
    }
}